Onthophagus hircus, Billberg, 1815

Rossini, Michele, Vaz-De, Fernando Z. & Zunino, Mario, 2018, Toward a comprehensive taxonomic revision of the “ hirculus ” group of American Onthophagus Latreille, 1802 (Coleoptera, Scarabaeidae, Scarabaeinae), European Journal of Taxonomy 432, pp. 1-21 : 9-12

Taxonomy of the hircus group

While informative morphological characters for taxonomic and phylogenetic purposes have been sought on several body parts of the beetles, including wings and mouthparts, the morpho-anatomical traits observed on the external body and genital organs revealed to be very useful in defining five speciescomplexes, whose taxonomy and geographical ranges are provided below (names, descriptions and illustrations of new species, as well as new synonymic notes will be provided in forthcoming articles):

C urvicornis complex

Onthophagus curvicornis Latreille, 1809 , O. incensus Say, 1835 , O. nitidior Bates, 1886 , O. stockwelli Howden &Young, 1981 , O. batesi Howden &Cartwright, 1963 , O. janthinus Harold, 1875 , O. acuminatus Harold, 1880 , O. tristis Harold, 1873 , O. striatulus striatulus (Palisot de Beauvois, 1809) , O. striatulus floridanus Blatchley, 1928 . Six new species have been identified within the complex.

Hircus complex

Onthophagus hircus Billberg, 1815 , O. ptox Erichson, 1847 , O. aeneus Blanchard, 1846 , O. bidentatus Drapiez, 1819 , O. marginicollis Harold, 1880 , O. antillarum Arrow, 1903 , O. buculus Mannerheim, 1829 , O. ranunculus Arrow, 1913 . At least five new species must be included in this complex.

Ophion complex

Onthophagus ophion, Erichson, 1847 and five new species to be described.

Osculatii complex

Onthophagus osculatii Guérin-Méneville, 1855 , O. nyctopus Bates, 1886 , O. steinheili Harold, 1880 , O. transisthmius Howden & Young, 1981 , O. ophion confusus sensu Boucomont, 1932 [species propria], O. insularis Boheman, 1858 , O. basicarinatus Rossini, Vaz-de-Mello & Zunino, 2018 and O. chacoensis Rossini, Vaz-de-Mello & Zunino, 2018 .

Rubrescens complex

Onthophagus rubrescens Blanchard, 1846 , O. haematopus Harold, 1875 , O. onorei Zunino & Halffter, 1997 . At least four new species must be included in this complex

Remarks

The publication dates of the species authored by Blanchard (i.e., O. aeneus and O. rubrescens ) and Latreille ( O. curvicornis ) are corrected according to Evenhuis (1997) and Bousquet (2016), respectively.

Unlike Zunino & Halffter (1997), we did not include O. crinitus Harold, 1869 and its subspecies O. crinitus panamensis Bates, 1886 in the hircus group, as their external morphology and genital organs lead us to consider them to be related to the species of the gazellinus group (comments based on the ongoing revision of the species group).

Furthermore, O. embrikianus Paulian, 1936 , O. nabeleki Balthasar, 1939 , O. schunckei Paulian, 1936 and O. catharinensis Paulian, 1936 , which were considered valid species names within the hircus group by Zunino & Halffter (1997), are here considered to be junior synonyms of species assigned to this group. These synonymies will be properly discussed throughout the taxonomic revision of the speciescomplexes.

Identification key to the species-complexes of the hircus group

1. Foretibia of male very slender and elongated, apical and internal margin with a distinct and acuminate tooth ( Fig. 3A ). If foretibia of male lacks a distinct apical tooth, then cephalic horns short, triangular and placed in the midline of the eyes (Costa Rica), body metallic blue (southeastern Brazil) or covered by long and dense hairs (southeastern Brazil to Uruguay). Pronotal punctures either simple or associated with small granules (one species and its subspecies from USA). From northern USA to northern Peru (through northern Venezuela), two species from southeastern Brazil to northern Uruguay ……… curvicornis complex

– Foretibia of male not very elongated, apical and internal tooth obtuse to obsolete ( Fig. 3B ). If foretibia of male very slender and with apical tooth acuminated, then cephalic horns strongly curved and embracing pronotal protuberance, always placed near the posterior side of the eyes (one species from Ecuador and Peru). Body neither metallic blue nor covered by long hairs. Body simply punctuated, granulated or with asperous punctures. From Central (Costa Rica) to South America, including Lesser Antilles …………………2

2. At least apex of elytra with granulose to asperous punctures associated with short and straight setae ( Fig. 3C ). If elytral interstriae devoid of any granules, then male with a central carina between cephalic horns (one species from Peru and Bolivia). Elytra either single-coloured (black, testaceous, dark brown, dark green) or odd interstriae clearly darker ( Fig. 3C ). Elytral tegument opaque to very weakly shining. From Panama to central Argentina ……………… hircus complex

– Elytra without granules or asperous punctures, conspicuous setae – when present – only associated with the punctures of lateral interstriae (VI–VII). Cephalic horns of male not connected by a central carina. Elytral interstriae never with alternate colours, either evenly coloured or disc clearly lighter than borders, some species with paler to reddish spots at the base and apex ( Fig. 3D–E ) ………3

3. Clypeus of male always triangular and elongated forward, clypeal margin truncated to narrowly rounded at middle, cephalic horns simple, straight and slightly bowed forward or feebly curved inward. Pronotum always with a longitudinal and distinct sulcus at least on the posteromedial region ( Fig. 3F ). Elytra shining, one species with discal interstriae (I–III) slightly opaque (Peru). Small to medium-sized species (body length 4–7 mm). Body reddish brown to black with reddish spots on the humeral umbones, or pronotum metallic dark-green and elytra black to testaceous on the disc and darker at the borders. From northern South America (Colombia, Venezuela and Guianas) to northern Argentina ……………… rubrescens complex

– Clypeus of male evenly curved, sub-trapezoidal or squared, if triangular, then major male either with cephalic horns carinate at the base ( Fig. 3G ) or pronotum not distinctly sulcate (at most slightly flattened or very weakly sulcate on the posteromedial region). Elytra opaque, sericeous to feebly shining, always entirely microreticulated ……………………………………………4

4. Clypeus of male wide, curved to obtusely squared ( Fig. 3H ), fronto-clypeal carina always absent in major male. Cephalic horns simple and slightly curved. Lateral margins of pronotum either evenly curved or slightly concave near anterior angles ( Fig. 3H ), anteromedial pronotal protuberance widely rounded between cephalic horns. Articles of the antennal club elongated ( Fig. 3I ); if antennal club normal, then basal half of elytra orange to testaceous and apex black. From Ecuador to Bolivia, one species known from the Guiana Shield ………… ophion complex

– Clypeus of male slightly elongated forward, triangular, trapezoidal or curved, male of two species with fronto-clypeal carina. Cephalic horns straight to very strongly curved and embracing the pronotal protuberance, one species with horns carinate at the base ( Fig. 3G ). Lateral margins of pronotum always evenly curved, anteromedial pronotal protuberance narrowly rounded, conical or very weak between cephalic horns; if widely rounded, then metasternal disc strongly punctuated ( Fig. 3K ). Articles of the antennal club normal ( Fig. 3J ). From Costa Rica to Bolivia, two species reaching eastern Amazonia ……… osculatii complex

Remark

The northern distribution of the osculatii complex is still rather doubtful, as throughout our extensive study we found an old specimen of O. nyctopus from Mexico (Sonora), which is here considered to be a possible mislabelling. So, at this stage, we prefer to consider the Costa Rican localities to be the northernmost limits of distribution of this complex. Nevertheless, the question is discussed more in depth in the taxonomic revision of the osculatii complex ( Rossini et al. 2018).

Figures

Fig. 3. A. Protibial apical tooth acuminate. B. Protibial apical tooth obtuse. C. Details of the elytral interstriae of Onthophagus marginicollis Harold, 1880 (hircus complex). D–E. Detail of the elytral paler spots. F. Pronotal sulcus of O. haematopus Harold, 1875 (rubrescens complex). G. Detail of the basal carina of the cephalic horns. H. Shape of the clypeus and lateral margin of pronotum of a species of the ophion complex. I. Right antenna of species of the ophion complex. J. Right antenna of species of the osculatii complex. K. Detail of the metasternal punctuation of a species of the osculatii complex. Scale bars: 1 mm.